6. Link-Layer Transmission of Datagrams

Source-specific multicast packets are transmitted on link-layer networks as specified in RFC 1112 for IPv4 and as in [ETHERv6] for IPv6. On most shared-medium link-layer networks that support multicast (e.g., Ethernet), the IP source address is not used in the selection of the link-layer destination address. Consequently, on such a network, all packets sent to destination address G will be delivered to any host that has subscribed to any channel (S,G), regardless of S. Therefore, the IP module MUST filter packets it receives from the link layer before delivering them to the socket layer.